Cholesteatoma

Cholesteatoma is an abnormal, destructive accumulation of keratinizing squamous epithelium in the middle ear and mastoid. Despite the name, it is not a tumor and it contains no cholesterol crystals in the modern pathological sense — the term is a historical misnomer that has persisted in clinical usage. Left untreated, cholesteatoma slowly but relentlessly erodes the ossicles, mastoid air cells, and surrounding bone through enzymatic and pressure mechanisms, leading to progressive hearing loss and potentially life-threatening intracranial complications.

Table of Contents

  1. What Is Cholesteatoma?
  2. Types: Acquired vs. Congenital
  3. Pathophysiology and Bone Erosion
  4. Symptoms and Clinical Presentation
  5. Diagnosis and Imaging
  6. Ossicular Chain Destruction
  7. Complications
  8. Surgical Treatment
  9. Canal Wall Up vs. Canal Wall Down
  10. Second-Look Surgery and Residual Disease
  11. Recidivism and Recurrence
  12. References & Research
  13. Featured Videos

What Is Cholesteatoma?

A cholesteatoma is a cystic structure lined by stratified squamous keratinizing epithelium — essentially skin that has migrated or grown into a location where it does not belong. Normally, the skin of the ear canal migrates outward (a process called epithelial migration), carrying debris away from the eardrum. In cholesteatoma, this migration is disrupted: keratinized squames accumulate in the middle ear or mastoid, forming an expanding mass of concentric keratin layers surrounding a central core of desquamated debris.

The mass appears as a pearlescent white lesion on otoscopic examination when visible. Its margins may produce a foul-smelling, cheesy discharge when infected. The term "cholesteatoma" was coined by Johannes Müller in 1838 based on the lesion's gross appearance, which he thought resembled fatty (cholesterol-containing) material.

Cholesteatoma is not a malignancy, but its behavior is locally aggressive. The epithelium stimulates the production of collagenase, matrix metalloproteinases (MMPs), and interleukins that dissolve the surrounding bone through both enzymatic digestion and osteoclast activation. This destructive capacity means that the goal of treatment is always surgical eradication.

Types: Acquired vs. Congenital

Acquired Cholesteatoma (90%)

Acquired cholesteatoma forms in the setting of chronic otitis media with middle ear and Eustachian tube dysfunction. Two subtypes are recognized:

Primary Acquired (Pars Flaccida / Attic Cholesteatoma)

The most common form. Chronic negative pressure in the middle ear — caused by Eustachian tube dysfunction — draws the pars flaccida portion of the tympanic membrane (the superior, less-taut portion) inward, forming a retraction pocket. Over years, the pocket deepens into the epitympanum (attic), accumulating keratin debris that cannot self-clean. This retraction pocket theory is the dominant mechanistic explanation for primary acquired disease. Early otoscopy reveals a subtle attic retraction pocket that can be mistaken for a simple perforation.

Secondary Acquired

Squamous epithelium migrates through a pre-existing perforation of the tympanic membrane — typically a marginal perforation at the posterosuperior quadrant — into the middle ear space. This is less common than the retraction pocket mechanism.

Congenital Cholesteatoma (10%)

Congenital cholesteatoma presents as a white, pearlescent mass visible through an intact tympanic membrane in children, typically discovered incidentally. It arises from remnant embryonic epithelial rests (Michaels' bodies) that normally involute during fetal development. Typical location is the anterosuperior quadrant of the middle ear, distinguishing it from the posterosuperior location of acquired disease. There is no history of otitis media, ear infections, or tympanic membrane perforation. Mean age at diagnosis is 4–7 years.

Pathophysiology and Bone Erosion

The destructive mechanism of cholesteatoma involves two interacting processes:

Enzymatic Bone Destruction

Cholesteatoma epithelium and the inflammatory cells it attracts (macrophages, mast cells) secrete elevated levels of matrix metalloproteinases (MMP-2, MMP-9), cathepsins, and various interleukins (IL-1α, IL-6, TNF-α). These enzymes directly dissolve collagen in the ossicular ligaments, periosteium, and surrounding bone matrix.

Pressure-Mediated Resorption

The expanding keratin mass exerts continuous pressure on adjacent bony structures, activating osteoclasts at the bone-lesion interface. This combination of enzymatic and pressure-driven resorption explains why cholesteatoma erodes bone at a rate disproportionate to its size.

The incus long process is the most vulnerable ossicle because of its tenuous blood supply and central position in the erosion pathway. It is the ossicle most commonly destroyed by cholesteatoma, followed by the stapes superstructure. The malleus handle is relatively protected and often remains intact until disease is extensive.

Symptoms and Clinical Presentation

Cholesteatoma is often slowly progressive and may be surprisingly asymptomatic until ossicular destruction or complications occur.

Recurrent or Chronic Ear Discharge

The hallmark presenting symptom is chronic, foul-smelling otorrhea that fails to clear completely with antibiotic eardrops. The discharge has a characteristic fetid odor from the anaerobic bacteria colonizing the keratin debris (particularly Pseudomonas aeruginosa and Proteus mirabilis). Patients often report multiple courses of antibiotics with only partial improvement.

Conductive Hearing Loss

Progressive conductive hearing loss (CHL) results from ossicular discontinuity or the mass effect of the cholesteatoma filling the middle ear space and damping tympanic membrane vibration. A large cholesteatoma may paradoxically improve sound transmission by bridging an ossicular gap (the "shell-through" effect) — a discovery that can delay the diagnosis.

Ear Fullness and Otalgia

A sensation of fullness or pressure in the affected ear is common. Pain is unusual in uncomplicated cholesteatoma but may indicate active infection or impending complications such as mastoiditis.

Otoscopic Findings

The classic appearance is a white, cheese-like mass visible in the attic (pars flaccida region) through an otoscope. Squamous debris may be seen extending from a retraction pocket. A marginal perforation in the posterosuperior quadrant with white pearlescent material is highly suggestive. The examiner must systematically assess the entire tympanic membrane, including the attic and posterior annulus, as early lesions can be subtle and obscured by otorrhea.

Diagnosis and Imaging

Otoscopy and Microscopy

The definitive diagnosis is clinical: direct visualization of the cholesteatoma sac on otoscopy or microscopy (operating microscope or otoendoscope). All patients with suspected cholesteatoma require formal audiometric evaluation including pure-tone audiometry and tympanometry.

High-Resolution CT of the Temporal Bone (HRCT)

HRCT is essential for surgical planning. It defines:

CT cannot reliably distinguish cholesteatoma from granulation tissue or middle ear effusion based on density alone, but its anatomical detail is indispensable for the surgeon.

Diffusion-Weighted MRI (DWI)

Non-echo-planar DWI (non-EPI DWI) has emerged as the most accurate non-invasive tool for detecting residual or recurrent cholesteatoma after surgery, with sensitivity and specificity exceeding 90%. Cholesteatoma keratin shows restricted diffusion (bright on DWI, dark on ADC map), distinguishing it from scar, effusion, and granulation tissue. DWI has largely replaced planned second-look surgery at many centers for post-operative surveillance.

Ossicular Chain Destruction

Cholesteatoma destroys ossicles in a predictable sequence determined by tumor extension from the epitympanum:

  1. Incus long process: most commonly eroded first (80–90% of cases with ossicular involvement); its distal segment has a poor blood supply from the stapes end
  2. Stapes superstructure (crura): second most common; erosion here produces a significant air-bone gap and increases the risk of perilymphatic fistula and sensorineural hearing loss during surgery
  3. Malleus handle: more resistant; erosion here suggests extensive cholesteatoma

Ossicular reconstruction (ossiculoplasty) is performed at the time of cholesteatoma removal or staged at a second procedure. Partial ossicular replacement prostheses (PORPs) replace the incus-stapes connection; total ossicular replacement prostheses (TORPs) replace the entire ossicular chain when the stapes arch is absent. Success rates (post-operative air-bone gap <20 dB) are approximately 60–80% for PORPs and 50–70% for TORPs at experienced centers.

Complications

Untreated or inadequately managed cholesteatoma can produce potentially life-threatening complications from erosion into adjacent structures:

Labyrinthine Fistula

Erosion of the bony labyrinthine capsule — most commonly the lateral semicircular canal — creates a perilymph fistula. This is the most common intratemporal complication (incidence 5–10%). Clinically, it produces sudden sensorineural hearing loss and episodic vertigo provoked by changes in middle ear pressure (positive fistula test / Hennebert sign). Intraoperative management is challenging because opening the fistula risks irreversible SNHL.

Facial Nerve Palsy

Erosion of the bony fallopian canal — typically at the horizontal (tympanic) segment or second genu — exposes and compresses the facial nerve. The incidence is 2–5% in untreated cases. Presenting as progressive ipsilateral peripheral facial weakness, it represents a surgical emergency requiring prompt decompression.

Mastoiditis and Coalescent Mastoiditis

Secondary infection of mastoid air cells produces postauricular swelling, erythema, and anterior displacement of the auricle. Coalescent mastoiditis (breakdown of septa between air cells) may require urgent mastoidectomy.

Intracranial Complications

These are rare (1–2%) but potentially fatal:

Surgical Treatment

Surgery is the only definitive treatment for cholesteatoma. The goals, in order of priority, are:

  1. Eradication of disease: complete removal of all cholesteatoma matrix to prevent recurrence
  2. A safe, dry ear: anatomically stable middle ear that resists future infection and recolonization
  3. Hearing reconstruction: ossiculoplasty to restore the ossicular chain

Tympanomastoidectomy — surgical exploration and exenteration of the mastoid air cell system — is the standard operative framework, with the specific technique chosen based on disease extent, mastoid pneumatization, and patient factors.

Canal Wall Up vs. Canal Wall Down

The central surgical controversy in cholesteatoma management is whether to preserve the posterior external auditory canal wall (canal wall up, CWU) or remove it (canal wall down, CWD / modified radical mastoidectomy).

Canal Wall Up (CWU) / Intact Canal Wall Mastoidectomy

The posterior bony ear canal wall is preserved, maintaining near-normal anatomy. Advantages: better hearing reconstruction outcomes, no open mastoid cavity requiring lifelong maintenance, can use bone-anchored hearing aids if needed. Disadvantages: higher recidivism (residual or recurrent cholesteatoma) rate of 10–40%; requires planned second-look surgery or serial DWI surveillance to detect residual disease hidden behind the intact wall.

Canal Wall Down (CWD) / Modified Radical Mastoidectomy

The posterior canal wall is removed, creating a large, open mastoid cavity (mastoid bowl) that is exteriorized through the ear canal. The Eustachian tube is obliterated. Advantages: lower recidivism rate (5–15%); the entire cavity can be inspected at clinic visits; suitable for extensive disease or in patients unlikely to attend follow-up. Disadvantages: the open cavity requires regular clinic debridement and lifelong water precautions; hearing reconstruction is less reliable; cavity problems (chronic discharge, erosion of the mastoid tip, inadequate meatoplasty) occur in 10–30% of cases.

Mastoid Obliteration

Obliteration of the mastoid cavity with bone pâté, hydroxyapatite, or cartilage after CWD reduces the burden of cavity management and can improve hearing outcomes. Various obliteration techniques are used at different centers; outcomes depend heavily on surgeon experience.

Second-Look Surgery and Residual Disease

In CWU tympanomastoidectomy, planned second-look surgery at 9–18 months was historically standard to detect and remove residual cholesteatoma not visible at the primary operation. Reported residual rates at second look range from 15–40% in adult series and up to 50% in pediatric cases.

Non-echo-planar DWI MRI has largely replaced routine second-look surgery at centers where it is available and where the surgeon is confident in intraoperative technique. A negative DWI scan at 18 months post-operatively has a negative predictive value of approximately 95% for residual cholesteatoma >3 mm. DWI is less reliable for small (<3 mm) residuals and for lesions near metallic ossicular prostheses.

Recidivism and Recurrence

It is important to distinguish:

Recurrence rates are higher in children (immature Eustachian tube function, longer time horizon for disease) and in patients with extensive primary disease. Long-term follow-up — minimum 5 years for CWU cases — is essential. Some surgeons advocate lifetime annual surveillance given the lifelong risk of recurrence, particularly in the pediatric population.

References & Research

Key Research Papers

  1. Olszewska E, Wagner M, Bernal-Sprekelsen M, et al. Etiopathogenesis of cholesteatoma. Eur Arch Otorhinolaryngol. 2004;261(1):6–24. PMID: 14600799
  2. Tos M. A new pathogenesis of mesotympanic (congenital) cholesteatoma. Laryngoscope. 2000;110(11):1890–1897. PMID: 11081610
  3. Persaud R, Hajioff D, Thevasagayam MS, et al. Keratosis obturans and external ear canal cholesteatoma: how and why we should distinguish between these conditions. Clin Otolaryngol Allied Sci. 2004;29(6):577–581. PMID: 15533132
  4. Kuo CL, Shiao AS, Yung M, et al. Updates and knowledge gaps in cholesteatoma research. Biomed Res Int. 2015;2015:854024. PMID: 25685789
  5. Vartiainen E. Factors associated with recurrence of cholesteatoma. J Laryngol Otol. 1995;109(7):590–592. PMID: 7561468
  6. Ikeda M, Yokoi H, Yoshida M, Furukawa M. Surgical outcome of canal wall-up and canal wall-down mastoidectomy for extensive cholesteatoma with low lying dura. J Laryngol Otol. 1999;113(4):314–318. PMID: 10474671
  7. Yung M, Tono T, Olszewska E, et al. EAONO/JOS Joint Consensus Statements on the Definitions, Classification and Staging of Middle Ear Cholesteatoma. J Int Adv Otol. 2017;13(1):1–8. PMID: 28360372
  8. Vercruysse JP, De Foer B, Somers T, et al. The value of diffusion-weighted MR imaging in the diagnosis of primary acquired and residual cholesteatoma: a surgical verified study of 100 patients. Eur Radiol. 2006;16(7):1461–1467. PMID: 16521014
  9. Saleh HA, Mills R. Classification and staging of cholesteatoma. Clin Otolaryngol Allied Sci. 1999;24(4):355–359. PMID: 10474209
  10. Quaranta A, Cassano M, Quaranta N. Facial palsy associated with cholesteatoma: a review of 24 cases. Otol Neurotol. 2007;28(3):405–407. PMID: 17414059
  11. Stapleton AL, Tyler MA, Lambert PR. Effect of operative approach on outcomes in pediatric cholesteatoma. Laryngoscope. 2016;126(11):2597–2601. PMID: 27027671
  12. Mustafa A, Taibah A, Pinna M, Russo A, Mancini F. Postoperative complications of cholesteatoma surgery: a case series. Otol Neurotol. 2018;39(3):349–355. PMID: 29432346

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Research Papers

The following PubMed topic searches retrieve current peer-reviewed literature on Cholesteatoma.

  1. Cholesteatoma surgery outcomes
  2. Cholesteatoma DWI MRI detection
  3. Cholesteatoma canal wall recurrence
  4. Congenital cholesteatoma pediatric
  5. Cholesteatoma bone erosion mechanisms
  6. Cholesteatoma ossiculoplasty hearing reconstruction
  7. Cholesteatoma intracranial complications
  8. Cholesteatoma second-look surgery residual

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Connections

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